Worth studied medicine in Oxford (matriculated 1693), Leiden and Utrecht (MD 1701) before practising as a doctor in Dublin.
A financial windfall from his uncle William helped him to establish a large book collection, bought from places such as London, the Netherlands, France and Dublin, in addition to those he had inherited from his father and grandfather.
On his death the collection consisted of some 4,400 books, many on medicine, dating back in some cases to the fifteenth century.
Worth left his library, then valued at £5,000, to Dr Steevens' Hospital in Kilmainham, of which he was a governor.
He was a friend and contemporary of such people as Jonathan Swift, and his library is remarkable, not only for its size and variety, but also for the condition of the books, some of which are hundreds of years old but appear almost new.